With increasing advances in the information industry, all types of electronic products are designed and made to meet users' requirements. For computers, many different modules also have to be integrated to meet this demand. The general home use desktop computers, notebook computers or standalone servers often encounter a problem of data storage being saturated but having no room for expansion. Hence to integrate the external storage devices has become one of the research and development focuses in the information industry these days.
Refer to FIG. 1 for a present external storage device. The integrated structure must include a plurality of electronic base members such as information storage units, power supply unit, logic processing unit, radiation unit and bus connection unit. Compared with a general single storage device (such as hard disk retrieval rack), the main consideration for integration is to provide an external power supply to drive the external storage device and also provide a radiation unit to maintain a desired internal temperature for the storage device so its operation performance can be maintained at a desired level. However such device cannot get rid of the electric connection adopted on the general computer host. Aside from the information storage units that can employ the retrieval connection type to achieve the convenience of connection without cables, other electronic base members still have to resort power cords or bus flat cables to connect the logic and processing unit and the radiation unit, and the bus connection unit. Such type of assembly takes a lot of working time and operations. In the event of damages happened, the whole set of host casing must be disassembled, and the connection cables have to be removed for repairs and replacement. It also cannot enjoy the benefits of hot-swappable technique and function for the electronic base members. In addition, the connection cables often have extra length, and the host casing must reserve an additional space to accommodate the extra connection cables. As a result, the total size of the device is too big and is not convenient to install or carry. It also does not meet the prevailing trend that demands compact size. Moreover, the extra connection cables hinder the radiation unit to draw and disperse heat from the interior of the device. This directly affects the operation performance of the external storage device.